Vacuum coagulation probe for atrial fibrillation treatment

ABSTRACT

An embodiment of the invention includes a surgical device for coagulating soil tissue such as atrial tissue in the treatment of atrial fibrillation, atrial flutter, and atrial tachycardia. The surgical device can include at least one elongate member comprising conductive elements adapted to coagulate soft tissue when radiofrequency or direct current energy is transmitted to the conductive elements. Openings through said conductive elements are routed through lumens in the elongate member to a vacuum source to actively engage the soft tissue surface intended to coagulate into intimate contact with the conductive elements to facilitate the coagulation process and ensure the lesions created are consistent, contiguous, and transmural. The embodiments of the invention can also incorporate cooling openings positioned near the conductive elements and coupled with a vacuum source or an injection source to transport fluid though the cooling openings causing the soft tissue surface to cool thus pushing the maximum temperature deeper into tissue. The embodiments of the invention can also incorporate features to tunnel between anatomic structures or dissect around the desired tissue surface to coagulate thereby enabling less invasive positioning of the soft tissue coagulating device and ensuring reliable and consistent heating of the soft tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/135,010 filed Jun. 6, 2008 (now U.S. Pat. No. 9,603,657 issued Mar.28, 2017), which is a continuation of U.S. patent application Ser. No.11/096,205 filed Mar. 30, 2005 (now U.S. Pat. No. 7,410,487 issued Aug.12, 2008), which is a continuation of U.S. application Ser. No.10/172,296 filed Jun. 14, 2002 (now U.S. Pat. No. 6,893,442 issued May17, 2005), the contents of which are incorporated herein by reference inits entirety.

FIELD OF THE INVENTIONS

Embodiments of the invention relate to devices and methods for lessinvasive treatment of atrial fibrillation. More particularly, certainembodiments of the invention relate to ablation and/or coagulationprobes that utilize suction to ensure consistent and intimate tissuecontact. These vacuum-assisted coagulation probes are capable ofcreating transmural, curvilinear lesions capable of preventing thepropagation of wavelets that initiate and sustain atrial fibrillation,atrial flutter, or other arrhythmia substrate. The vacuum-assistedcoagulation probes facilitate less invasive surgery involvingthorascopic access and visualization to the target coagulation sites.Additionally, the vacuum-assisted coagulation probes of the inventionare suitable for coagulating soft tissues (e.g. of the atria to treatatrial fibrillation, atrial flutter, or other arrhythmia) through amedian stemotomy, lateral thoracotomy, intercostals port-access,mini-sternotomies, other less invasive approaches involving Xiphoidaccess, inguinal approaches, or sub-thoracic approaches adjacent thediaphragm. Alternatively, the vacuum-assisted coagulation probes can bemodified for catheter-based applications by elongating the shaft andaltering the diameters and other feature dimensions for intravascularaccess.

The vacuum-assisted coagulation probes can also be used to coagulateother soft tissues for cancer therapy in a wide-variety of applications(e.g. liver, prostate, colon, esophageal, gastrointestinal,gynecological, etc.), or shrinking of collagen in tissue structures suchas skin, tendons, muscles, ligaments, vascular tissue duringarthroscopic, laparoscopic, or other minimally invasive procedures.

Certain embodiments of devices and methods of the invention also enabletunneling though and/or dissecting soft tissue structures by injectingfluid (air, CO₂, saline, etc) in high intensity streams that separatetissue structures by disrupting fatty deposits, ligaments, adventitialtissue, or other structure that holds anatomic structures togetherwithout damaging the anatomic structure the device is dissecting free orotherwise exposing. These devices of the invention enable less invasiveaccess without having to manually dissect tissue structures to place thevacuum-assisted coagulation probes. As such, these fluid dissectingdevices are capable of tunneling through the pulmonary veins, separatethe pulmonary veins, the aorta, the pulmonary artery, and other anatomyfrom the atria to provide a path for the vacuum-assisted coagulationprobe to directly appose the atrial epicardium throughout the desiredlength the lesion is expected to span, which is required to createtransmural, curvilinear lesions. These embodiments may alternativelydissect other soft tissue structures during applications such asendoscopic saphenous vein harvesting, left internal mammary arterydissection, etc.

DESCRIPTION OF THE RELATED ART

Atrial fibrillation surgery involving radiofrequency, d.c., microwave,or other thermal ablation of atrial tissue has a limitation in thattissue contact throughout the length of the electrode(s) is/are notconsistent causing variability in the transmission of energy throughoutthe target length of ablated/coagulated tissue. This produces gaps ofviable tissue that promote propagation of wavelets that sustain atrialfibrillation, or produce atrial flutter, atrial tachycardia, or otherarrhythmia substrate. Another influence in the inability of existingthermal ablation probes to create complete curvilinear, transmurallesions is the presence of convective cooling on the opposite surface ofthe atrium producing a heat sink that decreases the maximum temperatureat this surface hereby preventing the lesions from consistentlyextending transmural through the entire wall of the atrium. This isespecially relevant during beating-heart therapies in which thecoagulation/ablation probe is placed against the epicardial surface, andblood flowing along the endocardium removes heat thus producing a largergradient between temperature immediately under the probe electrodesalong the epicardium and that at the endocardium. Increased tissuecontact is capable of reversing this effect by evoking a compression ofthe tissue that shortens the wall thickness of the atria, ensuring,consistent contact throughout the length of the electrode(s), andincreasing the efficiency of thermal conduction from the endocardium. Assuch a more consistent and reliable lesion is created.

BRIEF DESCRIPTION OF DRAWINGS

Several exemplary embodiments of the present invention, and manyfeatures and advantages of those exemplary embodiments will beelaborated in the following detailed description and accompanyingdrawings, in which:

FIGS. 1a to 1d show a top view, a side-sectional view taken along A-A ofFIG. 1a , a side view, and a bottom view of a vacuum coagulation probeembodiment of the invention;

FIGS. 1e and 1f show cross-sectional views taken along B-B and C-C ofFIG. 1 d;

FIGS. 2a and 2b show a side view and a bottom view of a vacuumcoagulation probe embodiment that incorporates tunneling/dissectingfluid injection capabilities;

FIGS. 2c and 2d show sectional views taken along B-B and C-C of FIG. 2a;

FIG. 2e shows a detailed view of region D taken from FIG. 2 b;

FIG. 3 shows a-side view of a vacuum coagulation probe embodimentdeflected or bent to engage the soft tissue surface;

FIGS. 4a to 4c show side views of a vacuum coagulation probe embodimentthat incorporates a movable insulation sheath to adjust the electrodelength and convective cooling pores;

FIG. 5 shows a posterior view of the heart and associated vasculaturewith a vacuum coagulation probe embodiment accessing a desired lesionlocation along the left atrium;

FIG. 6 shows a posterior view of the heart and associated vasculaturewith a vacuum coagulation probe embodiment used to create lesions alongthe left atrium and right atrium capable of treating atrialfibrillation;

FIG. 7a shows an anterior view of a heart and associated vasculaturewith a vacuum coagulation probe embodiment placed to access regions ofthe left atrium about the pulmonary veins;

FIG. 7b shows a region of the thoracic cavity with the heart removed,but associated vasculature in place, to show access sites along the leftatrium for a vacuum coagulation probe embodiment to create lesionscapable of treating atrial fibrillation;

FIG. 8a shows a side-sectional view of a vacuum coagulation probeembodiment with the vacuum pores actuated to ensure intimate andcomplete contact between a tissue surface and the probe electrode;

FIG. 8b shows a close-up side-sectional view of the vacuum coagulationprobe embodiment in FIG. 8a with the vacuum pores actuated to urge softtissue into intimate contact with the electrode, coagulation energytransmitted through the electrode into tissue to create a curvilinear,transmural lesion, and convective cooling pores to decrease the surfacetemperature of the soft tissue and urge the maximum temperature deeper;

FIG. 9 shows a perspective view of a vacuum coagulation probe embodimentthat incorporates a high intensity fluid injection system to tunnelbetween and/or dissect free anatomic structures;

DETAILED DESCRIPTION

A need exists for vacuum coagulation probe devices and methods thatcreate contiguous, curvilinear, transmural lesions in the atria to treatatrial fibrillation, atrial fibrillation, or other arrhythmia substrate.In addition, such devices and methods could simplify other soft tissuecoagulation procedures by ensuring intimate tissue contact wideprecisely and effectively heating a region of soft tissue. The neededtechnology also could enable certain procedures to be performed lessinvasive through limited incisions that previously required large, openincisions with inherent morbidity and risks to other anatomicstructures. Such inventive devices and methods thus could enablepatients to undergo such reparative or therapeutic surgical procedureswhile enduring less pain, expedited hospital stays, and shorterrehabilitative and recovery times.

The present invention relates to methods and devices that enablereliable and controlled coagulation of soft tissue during less invasiveprocedures. To accomplish this, the coagulation probe incorporatesvacuum conduits associated with the electrode(s) to urge the soft tissueinto intimate contact with the edges of the electrode(s) and ensureefficient transmission of energy capable of consistently and completelyheating a desired region of soft tissue. The vacuum coagulation probeembodiments of the invention also enable convective cooling of thetissue surface to move the maximum temperature deeper into tissue andcreate larger and deeper lesions. The vacuum coagulation probeembodiments of the invention can also incorporate tunneling and/ordissecting features capable of introducing the vacuum coagulation probebetween anatomic structures around the atria which would otherwise beinaccessible without mechanical dissection, and/or expose a region ofatria to produce consistent tissue contact, required to ensurecontiguous, transmural lesions.

The following is a detailed description of certain exemplary embodimentsof the inventions. This detailed description is not to be taken in alimiting sense, but is made merely for the purpose of illustratingcertain general principles of the inventions.

This patent application discloses a number of exemplary embodiments,mainly in the context of soft tissue coagulation accomplished thoughless invasive approaches (e.g. thoracoscopic, arthroscopic,laparoscopic, percutaneous, or other minimally invasive procedures), Thevacuum coagulation probe embodiments disclosed herein can produceintimate contact between a soft tissue surface and electrode(s) used totransmit energy capable of heating the soft tissue until irreversibleinjury is achieved making the soft tissue non-viable and unable topropagate electrical impulses, mutate, reproduce or other unwantedfunction. The vacuum coagulation probe embodiments also enablesupporting and/or repositioning the soft tissue during coagulation toprevent or minimize shrinking or other change in the shape of the softtissue associated with heat causing the collagen in the soft tissue todenature. The vacuum coagulation probe embodiments also address issuesrelated to inadequate access to the soft tissue during less invasiveapproaches by tunneling and/or dissecting the anatomic structures toproduce a path to the coagulation sites, and expose the surface of thesoft tissue. This capability is especially relevant when coagulatingatrial tissue along the posterior region of the heart, characteristic ofcreating lesions along the left atrial epicardium about the pulmonaryveins.

Nevertheless, it should be appreciated that the vacuum coagulation probedevices can be applicable for use in other indications involving devicesthat are used to coagulate soft tissue, and/or tunnel between or dissectanatomic structures where access to the tissue is limited by a smallopening into the cavity, confined space at the soft tissue interface,difficult to reach locations, or other anatomic limitation. Theembodiments of the invention can be configured for the human anatomy;however, it should be noted that the embodiments of the invention can,in some cases, be tailored to other species, such as canine, ovine,porcine, bovine, or horses, by changing the geometry and sizes of thestructures.

An additional benefit of vacuum coagulation probe devices can involvethe ease of deployment and the rapid healing post-procedure. The smallincision used to access the soft tissue during such proceduresaccelerates the healing process and reduces the visible scar. The vacuumcoagulation probe devices can be capable of being deployed through athoracostomy, thoracotomy, median sternotomy, mini-sternotomy,mini-thoracotomy, xiphoid access, subthoracic access, arthroscopic, orlaparoscopic approach, thereby potentially eliminating, the need forlong incisions to access the soft tissue and corresponding anatomicstructures.

The vacuum coagulation probe, and corresponding components, can befabricated from at least one rod, wire, band, bar, tube, sheet, ribbon,other raw material having the desired pattern, cross-sectional profile,and dimensions, or a combination of cross-sections. The rod, wire, band,bar, sheet, tube, ribbon, or other raw material can be fabricated byextruding, injection molding, press-forging, rotary forging, barrolling, sheet rolling, cold drawing, cold rolling, using multiplecold-working and annealing steps, casting, or otherwise forming into thedesired shape. The components of the vacuum coagulation probe may be cutfrom raw material by conventional abrasive sawing, water jet cutting,laser cutting, ultrasonic cutting, EDM machining, photochemical etching,or other techniques to cut the lumens, pores, ports and/or otherfeatures of the vacuum coagulation probe from the raw material.Components of the vacuum coagulation probe can be attached by laserwelding, adhesively bonding, ultrasonic welding, radiofrequency welding,soldering, spot welding, or other attachment means.

For several of the vacuum coagulation probe embodiments below, variouscomponents can be fabricated from at least one wire, tube, ribbon,sheet, rod, band or bar of raw material cut to the desired configurationand thermally formed into the desired 3-dimensional configuration. Whenthermally forming e.g. annealing) components, they can be stressed intothe desired resting configuration using mandrels and/or forming fixtureshaving the desired resting shape of the puncturing component, and heatedto between 300 and 600 degrees Celsius for a period of time, typicallybetween 15 seconds and 10 minutes. Alternatively, the components may beheating immediately prior to stressing. Once the volume of materialreaches the desired temperature, the component is quenched by insertinginto chilled or room temperature water or other fluid, or allowed toreturn to ambient temperature. As such the components can be fabricatedinto their resting configuration. When extremely small radii ofcurvature are desired, multiple thermal forming steps can be utilized tosequentially bend the component into smaller radii of curvature.

When fabricating the vacuum coagulation probe components from tubing,the raw material can have an oval, circular, rectangular, square,trapezoidal, or other cross-sectional geometry capable of being cut intotile desired pattern. After cutting the desired pattern of lumens,ports, and pores, the components can be formed into the desired shape,stressed, heated, for example, between 300° C. and 600° C., and allowedto cool in the preformed geometry to set the shape of the components, asdiscussed above.

Once the components are fabricated and formed into the desired3-dimensional geometry, they can be tumbled, sand blasted, bead blasted,chemically etched, ground, mechanically polished, electropolished, orotherwise treated to remove any edges and/or produce a smooth surface.

Holes, slots, notches, other cut-away areas, or regions of groundmaterial can be incorporated in the components to tailor the stiffnessprofile. Cutting and treating processes described above can be used tofabricate the slots, holes, notches, cut-away regions, and/or groundregions in the desired pattern to taper the stiffness along, focus thestillness along the length of, reinforce specific regions of, orotherwise customize the stiffness profile of the vacuum probecomponents.

FIGS. 1a to d show a top view, a side-sectional view taken along A-A, aside view, and a bottom view of a vacuum coagulation probe 2 embodimentof the invention. The vacuum coagulation probe 2 incorporates a shall 4that defines a linen 6, as shown in FIG. 1e . The shaft 4 may befabricated from a metal (e.g. titanium), metal alloy (e.g. stainlesssteel, spring steel, nickel titanium) PEBAX®, polyester, polyurethane,urethane, silicone, polyimide, other thermoplastic, thermoset plastic,or elastomer, or braided metallic wires covered with a polymer. Theshaft 4 is preferably fabricated from tubing having a diameter between0.040″ and 0.300″ and a wall thickness between 0.004″ and 0.080″depending on the type of material and stiffness requirements. The tubingmay have a circular cross-section, elliptical cross-section, rectangularcross-section, or other geometry depending on the stillnessrequirements, access characteristics, and other considerations. Theshaft 4 may be fabricated from multi-lumen tubing having two or morelumens serving specific functions. At its proximal end, the shaft 4 isbonded to a handle (not shown) that incorporates a port(s) 20 that feedsthe lumen(s) 6. The port(s) 20 may incorporate a bier adaptor(s) orother tubing connection to facilitate attaching IV tubing or otherfeeding tube capable of connecting to a vacuum source.

The handle (not shown) also houses at least one electrical connector 14to which wire(s) 12 are attached at the proximal end. The wire(s) 12 arerouted to the electrode(s) 8 to enable transmitting energy(radiofrequency, or direct current) to the electrode(s). Whentransmitting radiofrequency energy in unipolar fashion to a largesurface area, reference electrode placed apart from the coagulationelectrode, a single wire is routed to each electrode and connected to aradiofrequency generator. When transmitting d.c. or radiofrequencyenergy in bipolar fashion to electrode pairs, individual wires areconnected to each of two or more individual, closely-spaced electrodes.When utilizing resistive heating of the electrode- and relying onconduction to transfer heat to adjacent tissue, two wires are connectedto each electrode (e.g. resistive element in this case) spaced apart sothe entire length of the electrode heats to the desired temperature andthe heat is conducted to contacted tissue.

Temperature sensors (not shown) may be associated with each electrodewith wires routed along the shaft to the handle where they are connectedto an electrical connector (14) capable of transmitting the temperaturesignal to a radiofrequency generator with temperature monitoring orcontrol capabilities or a separate temperature monitor. U.S. Pat. No.5,769,847, entitled “Systems and methods for controlling tissue ablationusing multiple temperature sensing elements” and incorporated herein byreference, describes tissue coagulation systems utilizing multipleelectrodes and temperature sensor associated with each electrode tocontrollably transmit radiofrequency energy and maintain allelectrode(s) essentially at the same temperature.

The vacuum coagulation probe electrode(s) and associated temperaturesensors (not shown) may be connected so such a mechanism to controltransmission of radiofrequency energy to each electrode to control theheating of contacted soft tissue.

The electrode(s) 8 may be fabricated from one or more lengths of tubing(having a circular, elliptical, rectangular, or other cross-sectional)secured to the shaft 4 at one end and containing a cap at the other end.If more-than one electrode 8 is desired, multiple lengths of tubing maybe connected to the shaft 4 separated by Short lengths of insulativetubing material. Alternatively, the electrode(s) may be fabricated fromwire, having a circular, rectangular, elliptical, or othercross-section, coiled into a helix, interlaced into a mesh or otherconfiguration and placed over and secured to an electrode support.Another electrode configuration includes lengths of sheet or barmaterial bonded to an electrode support having a semicircularcross-section or other geometry that defines a lumen, with the electrodein place, that is linked to the shaft 4 lumen 6. This configurationexposes the electrode only along one side of the vacuum coagulationprobe and insulates the opposite side against transmission ofradiofrequency energy and/or heat. As shown in FIGS. 1b, 1d and 1f ,pores or holes 10 are created along one side of the electrode connectingthe lumen 6 of the shaft 4 to the external surface of the electrode(s)8. These pores 10 enable producing a vacuum against the soft tissuethroughout the length of electrode(s) 8 thereby ensuring intimate tissuecontact between the electrode(s) 8 and the soft tissue. The pores 10also produce edges along the electrodes commonly associated with highcurrent densities transmitted into the soft tissue. The combination ofcreating intimate tissue contact and directing the current densityprofile creates controlled and efficient heating of the soft tissuerequired when creating contiguous curvilinear, transmural lesions inatrial tissue (or other soft tissue). The pores may have a constantdiameter or vary in diameter or profile along the length of theelectrode to differ contact forces and/or current density profilesthroughout the length of the electrode(s) 8.

The electrode(s) 8 may be fabricated from metal (e.g. tungsten,titanium, platinum, gold), metal alloy (e.g. stainless steel, springsteel, nickel titanium, etc.), metals deposited over a carrier (e.g.gold-plated stainless steel, gold deposited polyimide, platinumdeposited polyester, etc.) or a combination of materials cut, withmethods described previously, to define pores, shaft 4 attachmentfeatures (e.g. threads, slots, etc.) or other features. The electrode(s)may have a circular, elliptical, rectangular, curved, flattened, orother profile depending on tile function of the electrode(s). Theelectrode(s) may be fabricated from elastic or superelastic materials sothey can be deflected upon exposure to an external force (e.g. actuationof the vacuum, manual beading, etc.), or be treated so the electrode(s)is/are malleable so the operator may tailor the electrode(s) to theanatomic structures. Similarly, the shaft 4, described above, may betreated so it is malleable.

FIGS. 2a and 2b show another vacuum coagulation probe embodiment used tocoagulate soft tissue during minimally invasive access (e.g.thoracoscopic, endoscopic, arthroscopic, laparoscopic, or otherapproach) into the body cavity. A conventional cannulae, trocar or otherpostal is used to access the cavity though the skin and underlyingtissues.

The vacuum coagulation probe (2) embodiment in FIGS. 2a, 2b2c, 2d, and2e incorporates a multi-lumen tubing shaft (4) that contains two lumens(6 and 16), The first lumen 6 links to pores (10) created in at leastone electrode (8), as shown in FIG. 2c . The electrode embodiment inFIGS. 2a 2b, 2c, 2d, and 2e preferably consists of a length of sheet orbar material, having a predetermined wall thickness, secured to themulti-lumen shaft tubing along one side of the shaft. The electrode(s)may fit inside notches created ill the shaft tubing that houses theelectrode(s), adhesively bonded to an opening(s) in the shaft,ultrasonically welded to an opening(s) in the shaft, laser welded, spotwelded Or secured to the shaft with, another process depending on thematerials used for the electrode(s), and the shaft. Alternatively, theelectrode(s) may be fabricated from a multi-lumen tubing having thedesired cross-section and secured to the shaft. For example, themulti-lumen electrode tubing may have the same cross-section profile asthe shaft to maintain consistency in the lumen mating apposition.Another configuration involves fabricating the electrode(s) and theshaft from a single length of conductive tubing (e.g. single lumen ormulti-lumen), or less conductive, tubing deposited or otherwise coveredwith a metallic coating. In these cases, the shaft region of the probeis covered with an insulative material to isolate the shaft from theelectrode(s). In the embodiment shown in FIG. 2a , the shaft ispreformed into an “S” configuration; alternatively, the shaft may beformed into any desired geometry depending on the access to the targetcoagulation location.

As shown in FIGS. 2a, 2c , and 9, lumen 16 defined by the multi-lumentubing routes a second port 22 at the handle to high velocity fluidinjection pores 18 at the distal end of the vacuum coagulation probe 2to enable separation and/or dissection of connective tissue, fattydeposits, or other tissue that covers target anatomic structures orholds the anatomy together. Injection of fluid through the high velocityfluid injection pores 18 produces high intensity streams (68) of fluid,as shown in FIG. 9, capable of disrupting certain connective tissues(70), fatty deposits, and other tissue without damaging vascular tissue(72 and 74), or other anatomic structures. As such, the vacuumcoagulation probe is capable of tunneling through anatomic structuressuch as the pulmonary veins, the pulmonary artery, the aorta, or otheranatomic structure to place the probe at any desired coagulationlocation and produce a clean surface of tissue for the probe to contactand improve the efficiency of coagulation by removing adventitia orother tissue. The fluid used to dissect and/or separate tissue mayconsist of saline, CO₂, air or other medium capable of being forcedthrough the shaft 4 lumen 16 and past the distal end injection pores 18to create high velocity streams. The injection pores 18 have a diameterbetween 0.0005″ and 0.040″ and are distributed throughout the distal endof the vacuum coagulation probe (or the sides) to direct the stream ofinjected high intensity fluid against the tissue to be dissected orseparated. The pores may be angled such that the streams (68) intersectea distance away from tile distal end of the probe to focus thedissection and/or tunneling force a specified distance from the distalend of the probe.

The embodiments described above may be treated so they are malleable andmay be deformed into a desired shape, as shown in FIG. 3, required toaccess the desired coagulation location and/or create the desired lesionlength, and shape. An alternative approach, not shown in the Figures, isto incorporate a steering mechanism in the vacuum coagulation probe. Thesteering mechanism may be used to deflect the entire electrode relativeto the shaft and/or a portion of the electrode. At least one pull-wirecan be secured to the electrode at the electrode to shaft junction ifthe electrode is to be deflected as a unit relative to the shaft, oralong the electrode up to the distal end of the probe if the electrodeis to be deflected. The opposite end of the pull-wire(s) are routed tothe handle where it is secured to an actuation knob, not shown, tomanually deflect the vacuum coagulation probe into a curve. The curveshape, angle and radius is defined by the distance along or from theelectrode(s) at which the pull-wire(s) is/are secured and the stiffnessrelationship between the shaft and the electrode(s). A guide-coil orother radially restraining component can be housed around thepull-wire(s) in the shaft to specify the stiffness of the shaft andfurther define the radius of curvature and angle of deflection of thedistal region of the probe as the pull-wires are actuated.

FIGS. 4a, 4b, and 4c show the distal section of another vacuumcoagulation probe (2) embodiment. This probe (2) incorporates at leastone electrode (8), one is shown in FIGS. 4a, 4b, and 4c , containingvacuum pores (10) defined as cuts though the at least one electrode (8).A moveable sheath 24 alters the length of the electrode(s) by insulatinga proximal region of the electrode(s) from tissue and covering pores(10) in the proximal region of the electrode (8) such that tissue is notforced against the electrode(s) in the isolated region. FIG. 4a showsthe probe (2) with the distal 15% of the electrode(s) exposed and usedto vacuum contact and coagulate tissue. FIG. 4b shows the probe (2) withthe sheath (24) retracted such that approximately 40% of theelectrode(s) is/are exposed. FIG. 4c shows the probe (2) with the sheathfurther retracted such that approximately 85% of the electrode is/areexposed. The sheath (24) may be manipulated relative to the electrode(s)at any location to predetermine the length of the tissue to becoagulated into a lesion. The probe (2) embodiment in FIGS. 4a, 4b , and4 c further includes convective cooling pores (26) that may be connectedto the vacuum lumen 6 such that actuation of the vacuum source not onlycauses the tissue to contact the electrode but produces a convectivecooling of the tissue surface at the electrode-tissue interface capableof cooling the tissue surface and urging the maximum tissue temperaturedeeper into the tissue. Alternatively, the convective cooling pores (26)may be connected to the high velocity fluid injection lumen (16), orother conduit, such that saline, CO₂, air, or other medium may beinjected through the electrode or adjacent the electrode to activelycool the electrode and/or the tissue surface immediately adjacent theelectrode and urge the maximum tissue temperature deeper into tissue.The velocity of the fluid injected, the volume of injected fluid, andthe temperature of the medium determines the amount of cooling and themagnitude of the effect upon tissue heating.

Existing atrial fibrillation coagulation or other soft tissuecoagulation treatment applications performed thoracoscopically,endoscopically, arthroscopically, laparoscopically, or with other lessinvasive approach tend to create incomplete curvilinear lesions becausethe desired lesion sites are inaccessible, contact to the tissue ispoor, and the temperature gradient from the contacted tissue surface tothe opposite tissue surface is dramatic; these conditions limit thecreation of contiguous, transmural, curvilinear, lesions. This isespecially the case when blood is flowing along the opposite tissuesurface producing a heat sink that cools that tissue surface furtheraffecting the temperature gradient and limiting the lesion depth. Assuch, the existing techniques can be inferior and have a higher rate ofarrhythmia persistence than the vacuum coagulation probe devices of theinvention. In addition, incomplete lesions during atrial fibrillationtreatment have been demonstrated to generate substrates for persistentatrial flutter and/or atrial tachycardia. For other applications, theinability to create consistent and complete lesions allows cancerouscells, or other disease substrates to prevail.

An approach for treating atrial fibrillation with the vacuum coagulationprobe (2) of the invention is shown in FIG. 5, The probe is insertedinto the thoracic cavity though ports placed in intercostal spaces, athoracotomy, a thoracostomy, a median sternotomy, a mini-sternotomy,xiphoid access port, a lateral subthoracic access site, or other lessinvasive surgical procedure. The probe (2) may contain high velocityfluid injection capabilities, as shown in FIGS. 2c and 9 and describedabove, to tunnel around or between vessels (72 and 74) such as theaorta, pulmonary artery, pulmonary veins (28), and/or other anatomicstructures by separating and/or dissecting connective tissue (70), fattydeposits, and/or other tissue without damaging the vasculature (72 and74). The probe (2) may be deflected or deformed into the desired lesionpattern, which in this case is circular or semi-circular passing aroundthe right superior pulmonary vein, the right inferior pulmonary vein,the left interior pulmonary vein, the left superior pulmonary vein, andterminating at the right superior pulmonary vein. Once placed, thevacuum source is actuated to apply a suction force through the vacuumpores (10) to urge the epicardium of the left atrium (36) into intimatecontact with the electrode(s) (8). It should be noted that the vacuumcoagulation probe can instead be placed against the endocardium of theatria during cardiopulmonary bypass procedures where the atria are openfor valve (mitral, tricuspid, and/or atrioventricular) repair orreplacement procedures or beating heat procedures where an introducerinto the atrium is obtained through an atrial appendage, the atrial freewall, the ventricle, a pulmonary vein, a vena cava, or other conduitthat may be closed upon completion of the coagulation procedure.

The entire length of the exposed electrode(s) is used to apply suctionthough the pores (10) to apply a vacuum force against the epicardium (orendocardium) and urge the tissue into engagement with the electrode(s).An insulative, movable sheath as shown in FIGS. 4a, 4b, and 4c may beused to alter the length of exposed electrode(s) and the target regionof tissue that Will be urged into engagement by the suction forces.

Then radiofrequency (or dc) energy is transmitted to the electrode(s) inunipolar or bipolar mode such that the current density is transmittedinto tissue adjacent the electrode(s) and ohmic heating causes thetissue adjacent the electrode(s) to heat and conduct the heat furtherinto the depths of tissue. Alternatively, the electrode(s) may befabricated from a resistive element in which radiofrequency (or d.c.)energy applied along the resistive element, between wire connections atopposite ends of the resistive element, heats the element and theintimate tissue to electrode(s) contact enable thermal conduction of theheat into the target soft tissue.

The transmission of energy in unipolar or bipolar mode causes the softtissue to heat which conducts further into adjacent soft tissue;alternatively the heating of a resistive element causes the resistiveelectrode(s) to heat which is then conducted into adjacent, contactedsoft tissue. As cardiac cells (and any muscle tissue) is heated above50° C. irreversible conduction block occurs and the cells becomenon-viable (Nath, et al. Cellular electrophysiologic effects ofhyperthermia, on isolated guinea pig papillary muscle: implications forcatheter ablation. Circulation. 1993; 88:1826-1831). As such, aconsistent, continuous length of atrial tissue extending from theepicardial surface to the endocardial Surface must be heated above 50°C. to treat atrial fibrillation.

For other applications involving coagulation of soft tissue to shrinkcollagen rich tissues or prevent shrinking of collagen tissues, heatingof the soft tissue must be controlled, which the vacuum coagulationprobe embodiments of the invention enable. Published studies evaluatingthe response of vessels (arteries and veins) to heat have focused on theability to permanently occlude-vessels. Veins have been shown to shrinkto a fraction of their baseline diameter, up to and including completeocclusion, at temperatures greater than 70° C. for 16 seconds; thecontraction of arteries was significantly less than that of veins butarteries still contracted to approximately one half of their baselinediameter when exposed to 90° C. for 16 seconds (Gorisch et al, Heatinduced contraction of blood vessels. Lasers in Surgery and Medicine,2:1-13, 1982; Cragg et al. Endovascular diathermic vessel occlusion.Radiology. 144:303-308, 1982). Gorisch et al explained the observedvessel shrinkage response “as a radial compression of the vessel lumendue to a thermal shrinkage of circumferentially arranged collagen fiberbundles”. These collagen fibrils were observed to denature, thus shrink,in response to heat causing the collagen fibrils to lose thecross-striation patterns and swell into an amorphous mass.

Embodiments of the invention prevent or limit the heat-inducedcontraction of such structures as the pulmonary veins by applying avacuum force capable of maintaining the position (e.g. diameter) of thevessel while heating the soft tissue. As such, the vessel is stented orsupported from the external surface as the tissue is heated above therequired 50° C., threshold without concern that the vessel mayaccidentally become stenosed due to the heat-induced contraction.

Alternatively, the vacuum coagulation probe embodiments directheat-induced contraction of such structures as tendons, skin or otheranatomy in which the therapy is designed to heat thereby denature thecollagen and shrink the tissue until the desired shape or effect isachieved. In addition, the vacuum coagulation probe can reposition thesoft tissue while heat is applied to the soft tissue to direct theshrinking and cause the collagen fibrils to reorganize reforming thesoft tissue into a desired shape.

FIG. 6 shows a posterior view of a heart with a vacuum coagulation probeembodiment placed between the right superior pulmonary vein 28 and thecoronary sinus 30 to create a lesion extending from the right superiorpulmonary vein to the right inferior pulmonary vein and finally endingat the coronary sinus. FIG. 6 shows this placement intersecting anotherlesion 40 previously created with the vacuum coagulation probeembodiment and extending from the left superior pulmonary vein to theleft inferior pulmonary vein and ending at the coronary sinus. FIG. 6also shows light atrial lesions created with the vacuum coagulationprobe extending from the superior vena cava to the inferior vena cava,and from the inferior vena cava to the tricuspid valve annulus locatedalong the atrial ventricular groove proximate the coronary sinusorifice. Such lesion patterns described above have been demonstrated toterminate atrial fibrillation provided they are contiguous, transmural,and extend to the barriers (e.g. the branching vessels, atrioventriculargroove, or other structure that inhibits electrical propagation).

FIGS. 7a and 7b show an anterior view of a heart and a cut away viewwith the heart removed having two vacuum coagulation probes 2 advancedbetween vascular structures to access the posterior region of the leftatrium about the pulmonary veins. As FIGS. 7a and 7b show, a firstvacuum coagulation probe accessing the heart from the anterior surfaceof the thoracic cavity between the aorta and the superior vena cava,adjacent the right superior pulmonary vein, past the right inferiorpulmonary vein, and down to the atria-ventricular groove; theelectrode(s) (8) create a lesion from the atria-ventricular groove alongthe right pulmonary veins. The second vacuum coagulation probe entersthe thoracic cavity and extends around the left ventricle of the heart,passes around the left inferior pulmonary vein, and intersects the firstvacuum coagulation probe. The electrode(s) for this probe extend alongthe left atrium around the left inferior pulmonary vein and terminatesat or past the lesion created with the first probe. It should be notedthat any pattern of curvilinear, transmural lesions may be created alongthe epicardial surface or the endocardial surface with the vacuumcoagulation probe embodiments of the invention. Other potential lesionpatterns capable of treating atrial fibrillation, which the vacuumcoagulation probe may replicate, me described in U.S. Pat. No. 6,071,279entitled “Branched structures for supporting multiple electrodeelements” and incorporated herein by reference.

FIGS. 8a and 8b show a side view and a close-up view of the vacuumcoagulation probe in FIGS. 4a, 4b, and 4c with the suction actuated tourge the epicardium (52) (or endocardium) into engagement with theelectrode(s) (8) about the vacuum pores (10). A contiguous transmurallesion extending from the epicardium 52) to the endocardium (54) iscreated spanning the length of the exposed electrode(s). A sheath (24)masks a proximal region of electrode(s) and associated vacuum pores tolimit the lesion to a desired length. Radiofrequency (or d.c.) energy istransmitted to the electrode(s) and into the contacted tissue. Thecurrent density pattern (64) has the highest values adjacent the edgesof the pores (10) because these edges represent a dramatic transitionfrom a conductive material to an insulative (or less conductive) regionproducing edge effects that result in high current density profiles. Asshown in FIG. 8b , convective cooling pores (26) connected through thevacuum lumen (6) or the injection lumen (15) can be placed along thelateral sides of the electrode(s) (8) to utilize suction of air or fluidor injection of cooled saline, CO₂, air or other media to produce asurface cooling of the epicardium and urge the maximum temperaturedeeper into the soft tissue. The suction force used to produce intimatecontact between the epicardial surface and the electrode(s) helpscounteract the effects of endocardial convective cooling caused by bloodflowing 58 along the endocardial surface taking heat away and coolingthe tissue adjacent the endocardium. The suction force compresses thetissue against the electrode(s) decreasing the depth of tissue (60)through which thermal conduction must extend. Suction also makes energydelivery more efficient by optimizing tissue contact throughout thelength of the electrode(s) such that regions of the electrode(s) not inintimate tissue contact do not hinder energy transmission for thoseregions that are in intimate contact, as is the case with conventionalapproaches. The incorporation of convective cooling pores (26) along thesides of the electrodes further affects the temperature gradient byutilizing a vacuum source or an injection source to flow a fluid medium(air, CO₂, saline, etc.) along the epicardial surface actively coolingthe surface and allowing more energy to be transmitted into the softtissue which correspondingly heats more tissue and urges the maximumtissue temperature deeper.

The embodiments of the invention described in this specification canalso be used for coagulating other soft tissues such as breast tissue,the liver, the prostate, gastrointestinal tissue, skin, or other softtissue for the coagulation of cancerous cells; or tendons, or othercollagen based soft tissue for the heat induced shirking or contraction.

Although the present inventions have been described in terms of thepreferred embodiments above, numerous modifications and/or additions tothe above-described preferred embodiments would be readily apparent toone skilled in the art. It is intended that the scope of the presentinventions extend to all such modifications and/or additions and thatthe scope of the present inventions is limited solely by the claims ofthe invention.

The invention claimed is:
 1. A method for coagulating a soft tissuecomprising: placing an elongate member against a surface of the softtissue, the elongate member comprising at least one lumen, at least oneelement, and at least one opening through the at least one element wherethe at least one opening is fluidly coupled to the at least one lumenthrough the at least one element; applying a vacuum source to produce avacuum in the at least one lumen and through the at least one opening tocause the soft tissue to contact a length of the at least one element atthe at least one opening; and transmitting energy using the at least oneelement to heat the soft tissue to create a contiguous lesion in thesoft tissue where a length of the contiguous lesion corresponds to thelength of the at least one element that contacts the soft tissue; andwherein said elongate member further comprises a non-conductive sheathcovering a length of the elongate member and movable relative to theelongate member, and placing the elongate member against the soft tissuesurface comprises advancing or retracting the non-conductive sheathrelative to the elongate member.
 2. The method of claim 1, wherein atleast one of the elongate member and said element are malleable suchthat upon exposure to an external force the at least one element deformsagainst the soft tissue surface and where suction from the vacuum sourceis applied to an entire exposed length of the at least one element inthe entire length of the at least one opening allowing coagulation ofthe soft tissue surface along the entire length of the at least oneopening.
 3. The method of claim 1, wherein placing the elongate memberagainst the soft tissue surface comprises tunneling or dissecting aroundpulmonary veins to engage the at least one element against a left atrialsurface associated with the pulmonary veins.
 4. The method of claim 1,where the at least one element comprises a bi-polar element.
 5. Themethod of claim 1, where the at least one element comprises a unipolarelement.
 6. A method for coagulating a soft tissue comprising: placingan elongate member against the soft tissue, the elongate membercomprising at least one vacuum lumen and at least one element, where theat least one element is in fluid communication with the at least onevacuum lumen and exposed at an opening in the elongate member; applyinga vacuum source to produce a vacuum in the at least one vacuum lumensuch that the vacuum passes through the at least one element to drawtissue in contact with a length of the at least one element;transmitting energy through the at least one element to create acontiguous lesion in the soft tissue where the contiguous lesion has alength that corresponds to the length of the at least one element thatcontacts the tissue; and wherein the elongate member further comprises anon-conductive sheath covering a length of the elongate member andmovable relative to said elongate member, and placing the elongatemember against the soft tissue comprises advancing or retractingnon-conductive sheath relative to the elongate member.